On most Mercedes the valves are Identical, so steal one from a +2000 W208/W220/W210 from the junk yard. Most cars have this valve inside the left rear inner fender..

This code can be nightmare along with P0455 "gascap code"...

If it comes on right away(second start like you say), but no drive you may have open or shorted line to the canister purge valve-easy fix

If it comes on after a drive cycle, you are in for it-In troubleshooting, You may end up where I'm at smoking the system up, and found a leak of intake vacuum on the plenum of the intake manifold on one of the rubber rings on a M119

I have been on it for months, but their is procedure in DAS to test these EVAP valves..

I will post some links that may help you later...

Martin

PS.. most of these valves just have two wires, and you can power it with 12v, and the valve is normally open, yet when powered if you blow on the nipple coming from the charcoal canister the valve should shut.. Current draw is low under an amp maybe more like 300mA... Some say you can clean the valve. Well, I tried that, and ruined mine...